MAYBE
MAYBE
TRS:
 {
        f(X1, X2, mark(X3)) -> mark(f(X1, X2, X3)),
  f(ok(X1), ok(X2), ok(X3)) -> ok(f(X1, X2, X3)),
      active(f(X1, X2, X3)) -> f(X1, X2, active(X3)),
     active(f(a(), b(), X)) -> mark(f(X, X, X)),
                active(c()) -> mark(a()),
                active(c()) -> mark(b()),
      proper(f(X1, X2, X3)) -> f(proper(X1), proper(X2), proper(X3)),
                proper(a()) -> ok(a()),
                proper(b()) -> ok(b()),
                proper(c()) -> ok(c()),
               top(mark(X)) -> top(proper(X)),
                 top(ok(X)) -> top(active(X))
 }
 DUP: We consider a duplicating system.
  Trs:
   {
          f(X1, X2, mark(X3)) -> mark(f(X1, X2, X3)),
    f(ok(X1), ok(X2), ok(X3)) -> ok(f(X1, X2, X3)),
        active(f(X1, X2, X3)) -> f(X1, X2, active(X3)),
       active(f(a(), b(), X)) -> mark(f(X, X, X)),
                  active(c()) -> mark(a()),
                  active(c()) -> mark(b()),
        proper(f(X1, X2, X3)) -> f(proper(X1), proper(X2), proper(X3)),
                  proper(a()) -> ok(a()),
                  proper(b()) -> ok(b()),
                  proper(c()) -> ok(c()),
                 top(mark(X)) -> top(proper(X)),
                   top(ok(X)) -> top(active(X))
   }
  Fail